Film Scanner Notes:

Each of the film scanners in the table has fans. Prices are
list price and discount from www.buy.com and www.bhvideo.com (and prices
may change, and may not include controller board and cable). And NewEgg.com
has a very good price on the Minolta Dual Scan IV. A higher
price does buy more scanner, better optics, infrared dust reduction,
better software, and also better dynamic range, giving
deeper noise-free detail from dark shadow tones in slides. Dynamic range
is quite important for slides, but less important if scanning negatives.

But the dynamic range spec is not shown here, because the
advertised number is unfortunately only marketing hype. There are no
standards for advertising this value. It is a totally meaningless number
as advertised. Don't assume 3.6 is better than 3.4, or that either is
achievable. It is not a performance spec, the scanner was not measured.
3.6 for 12 bits or 4.2 for 14 bits is the theoretical maximum,
simply the greatest possible value those bits could possibly hold, if all
else were theoretically perfect (see page 157). It assumes DMin is zero,
DMax is maximum, and noise is zero, all ridiculous. A false 3.6 cannot be
compared to a false 3.4. These may be fine scanners, but have other
reasons than this number to choose them.

Marketing's scan speed spec is not shown either, because
it is also not very meaningful. SCSI is faster than USB 1.1, especially
for 20-60 MB scans. Focusing can take a long time. Saving a very large
file also takes awhile. Don't be surprised at 3 minutes overall at
full resolution and 16 bits. There's lots of reasons, and computer
speed is a big factor too. Scanner exposure time is a bigger time factor
than interface bus, and this varies with film frame.

Maximum size 24 bit 35 mm film images are about:

2400 dpi

3400x2200 pixels

7.5 megapixels

22 MB

2820 dpi

3800x2600 pixels

9.9 megapixels

30 MB

4000 dpi

5600x3600 pixels

20 megapixels

60 MB

16 bit data will be twice this size in MB. You need at least 4 times
that much system memory, and 8 times is better for editing. If that image
is too large for the purpose, then try scanning at 1/2
or 1/4 or 1/8 of full
optical resolution, using even fractional divisors when possible.

Auto Focus is a motorized focusing method, and can compensate
for warped or buckled film frames. Other units are fixed focus.

Batch Scanning uses a motorized film feed mechanism to position
each film frame. This can allow automatic scanning of multiple images.
The table value shown is the number of frames: film strips /
mounted slides.

Some few Minolta and Nikon models have optional autofeeders for 50
mounted slides (about $500).

APS film size requires an optional hardware APS adapter (about
$120 to $250). These can batch scan the full APS roll. The Canon FS2710
APS adapter is manual and included.

The Multi-Scan feature can scan one frame multiple times
(typically 4 or 16 times scanned in one slow pass). Those images are
combined into one image, to average out the random scanner noise in the
image data. It is an important noise reduction technique to produce clean
dark tones from slides (even in scanners with so-called 4.2 dynamic range
too). Multi-Scan is not such an advantage for negatives, because negative
dark tones are inverted to the highlights where the noise is harder to
see. VueScan can multi-scan with some units that don't support
multi-scan.

Some scanners provide a fourth infrared hardware channel (RGB+IR)
to allow software to detect and remove dust, fingerprints, scratches and
other film damage. Such software is Digital ICETM and VueScan.
This causes a slight softening of image sharpness, but it is a popular
option, and many users consider it essential. Subsequent sharpening can help. IR does not work with
conventional B&W films, and often not so well with Kodachrome, but it does work on all other dye-based slides and negatives.

The Nikon units uniquely use LED illumination source instead of
a fluorescent lamp.

The Polaroid and Microtek 4000 dpi models are similar hardware, with
different software.